Perhaps you should try some spelling variations:
thanh day » thanh dat, thanh tay, thanh dam
va thanh » gia thanh, ban thanh, va tinh
te sach » toc sach
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
cac duc » cac du, cao duc, cac dac
cua tre » cua te, cua triet, dua tren
cuu tre » cau tren, cau treo

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky ((mang may) OR (nang cao)) hoi. hieu va cac duc va thanh day ((cua tre) OR (cuu tre))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky ((mang may) or (nang cao)) hoi. hieu va cac duc va thanh day ((cua tre) OR (cuu tre))~".
• Adding a wildcard symbol may retrieve word variants: te sach ky ((mang may) or (nang cao)) hoi. hieu va cac duc va thanh day ((cua tre) OR (cuu tre))*.